Wireless interfaces are increasing being used between devices as a means of transmitting data from one device to another. Many such wireless interfaces use radio transmission techniques. For example, the Institute of Electrical and Electronic Engineers (IEEE) has set forth several standards defining local and personal area wireless protocols and specifications. Some examples of these standards are known commonly by names such as WiFi, and by trade names such as Bluetooth.
Personal area networking, such as that substantially conforming to the IEEE 802.15.1 standard, is being increasingly used between devices meant to be used by the same person cooperatively. Examples of which include interfaces between cellular phones and earpieces, speakerphone devices, and automobile audio systems, interfaces between personal computers and wireless keyboards and other input devices, and so on. In some of these applications there can be a critical need to transmit data from one device to another, where latency must be minimized.
One example of such a critical application is in the link between a two way radio and an associated remote microphone device, as is common in public safety applications. Two way radios provide “push to talk” (PTT) operation, where the user can press a button on the device and commence speaking almost instantly, where the two-way radio commences transmitting the voice data as the user commences speaking. This kind of operation differs from other communication systems such as, for example, cellular telephony, where a call circuit must be set up, and the called party must answer a call at their end before the caller can commence speaking. In PTT systems, when the user presses the talk button, the radio begins transmitting, and radios receiving the transmission audibly reproduce the user's voice without requiring interaction from a user at the receiving radio.
Since the near-instant communication aspect of PTT operation is crucial, it is desirable to avoid any latency. However, conventional personal area networking protocols can introduce latency in several ways. For example, data sent to the personal area network protocol stack must be processed through the protocol stack. There are several layers of processing before the data is passed to the wireless adapter for transmission, and these layers of processing, while of adequate speed for most applications, can introduce an undesirable amount of latency in PTT applications. Furthermore, since PTT data may not be the only data being exchanged between a remote accessory and the two-way radio device, the protocol stack can subject PTT data to flow control procedures which introduce undesirable latency into the communication. Accordingly, there is a need for a means by which personal area networking techniques can be implemented in applications with critical latency considerations.